An unprivileged user could crash the server process,
resulting in momentary denial of service to other users, if
the server has been compiled with Asserts enabled (which is
not the default). Thanks to Akio Ishida for reporting this
problem.

Fix bug with row visibility logic in self-inserted rows
(Tom)

Under rare circumstances a row inserted by the current
command could be seen as already valid, when it should not
be. Repairs bug created in 7.4.9 and 7.3.11 releases.

Fix race condition that could lead to "file already exists" errors during pg_clog
file creation (Tom)